Turkish Salix species: Molecular phylogeny and morphology

This study provides a new insight into Turkish Salix L. systematics, using a molecular phylogeny and numerical morphometric analysis approach. Despite its economic importance for bioenergy, there is to date no record of any extensive study on this Turkish willow species. Twenty-four Salix species and one hybrid were subjected to molecular and morphometric evaluation, in which one gene region of the external transcribed spacer (ETS) of the 18S-26S nuclear ribosomal DNA and 11 morphological characters were analyzed using a Bayesian Analysis of Beast program and Multiple Correspondence Analysis (MCA) in R. The results indicate that Salix species in Turkey could be accurately classified at the subgenera level, considering the selected gene region and morphological traits (subgenus Salix and Vetrix). Life form, leaf shape (Dim 1) and bud scale (Dim 3) were highly discriminative at the subgenera level. The molecular and morphological data confirmed that the taxonomic position of Salix amplexicaulis needs to be changed as subgenus Salix. Additionally, the members of subgenus Salix, S. acmophylla and S. pentandroides were all clustered distantly from other species of the subgenus.